HEADS, YOU LOSE: Expect Eli Manning to sit Saturday’s preseason game after taking a brutal hit Monday against the Jets — opening a gruesome cut on his forehead. (Charles Wenzelberg/New York Post)

(Charles Wenzelberg/New York Post)

ALBANY — Eli Manning almost always plays, but he thinks the gash on his forehead will prevent him from competing in Saturday night’s preseason game against the Steelers, the Giants first home game at New Meadowlands Stadium.

The Giants’ $100 million quarterback needed 12 stitches to close a three-inch laceration that turned his Monday evening into a bloody horror movie outtake.

Manning yesterday underwent a battery of tests at the Hospital for Special Surgery in Manhattan, and although he said he passed all the tests and definitely does not have a concussion, the wound on his head will make it difficult to put on a helmet and take the field.

“They haven’t given me an exact time frame when I’ll be back,” Manning said on 1050 ESPN radio.

“I have a feeling I might be out this upcoming week just trying to get these stitches healed up. I don’t know when I’ll be able to put the helmet on. Hopefully I’ll be able to rig something up. I might have to bring out an old leather helmet to get some practice in this week. I don’t want to be sitting around doing nothing. I feel I can play. The helmet might be the only restriction right now.”

As for the tests, Manning said they were done to “make sure there’s no further damage to my brain or skull and stuff. Everything looks fine. That’s all good news.”

Manning last night returned here to training camp, but he’s not going to participate in practice until there’s no threat of re-opening the wound.

The freak play, caused by a Manning error in judgment, came early in the second quarter of a 31-16 preseason-opening victory over the Jets. The play call was a run up the middle for Brandon Jacobs, but Manning didn’t think the play was destined for success against the Jets defense and decided to change to a fade pass. The problem was, Manning didn’t alert everyone.

As Manning faded back, an unsuspecting Jacobs collided with him, knocking Manning off balance and loosening the chinstrap on his helmet. What followed was a vicious hit as linebacker Calvin Pace slammed Manning from behind, causing his helmet to fly off as he was thrust forward, head-first, into the facemask of safety Jim Leonhard. Immediately, Manning’s head was covered in red.

“I probably did panic a little bit — I saw it gushing out and put my hand on it and it went all over my hand and all over the place,” Manning said.

“I knew I fumbled the ball. I wasn’t looking to recover the football at the time. I was looking at the trainers and saying, ‘Hey, get out here, something’s going on.’ ”

Coach Tom Coughlin yesterday morning exchanged test messages with his quarterback, and Manning told him he was feeling “normal discomfort” from the trauma.

Asked when Manning would be able to practice, Coughlin said, “I’m not guessing on that. I’ll wait to see what the doctors will have to say.”

Manning said he was worried how he’d feel when he woke up but was relieved he did not have a headache. “My body and my mind and my head all feel very good,” he said on ESPN.

Manning joked his movie career might be enhanced.

“I think it might help it, now I can be the bad guy,” he said. “I have the full scar on the forehead. My [hair] part might not look the same, they had to shave a little bit of my head.”

As for when he can return to practice, Manning said “It’s just a matter of when I can put a helmet on and get the stitches taken out.”